Objects extending over a roadway, such as bridges, tunnels, overhead road signs, are recognized as obstacles in particular by radar sensors, without there being a reliable estimation from the radar data as to whether a vehicle can pass through said obstacle. Even when using mono-cameras this estimation is often difficult to be made.
DE 10234645 B4 shows a vertical stereo camera arrangement for a vehicle, by means of which a clearance height of a bridge can be estimated with sufficient accuracy from the position of the horizontal lower edge of the tunnel entry and the position of a horizontal edge between the tunnel front side and the roadway level. It is further stated that a combination of a horizontal and a vertical stereo arrangement enables all horizontal and vertical infrastructural components of road traffic to be captured and measured.
DE 10 2004 015 749 A1 also shows a device for determining the possibility for a vehicle to pass through. In front of an obstacle the clearance width and/or the clearance height are measured by means of a sensor unit. In addition it is proposed to monitor the course of the roadway ahead by means of a sensor of the sensor unit so as to be able to determine a height difference between an ascending roadway and the position of a beam spanning the roadway, if necessary.
DE 10 2009 040 170 A1 proposes to use a sensor unit with e.g. a stereo camera in order to determine a maximum clearance height and/or a minimum ground clearance and to drive a running gear actuator unit such that the maximum clearance height is not exceeded by the total height of the vehicle and the minimum ground clearance is adhered to, as long as this is possible for the region of the roadway to be passed through.
One approach to object recognition in stereo image data processing is shown by U. Franke et al. in 6D-Vision: Fusion of Stereo and Motion for Robust Environment Perception in Proceedings of DAGM-Symposium 2005, pp. 216-223. Here, the positions and velocities of many pixels are estimated simultaneously in three dimensions.
It is apparent that the methods and devices of the state of the art have disadvantages and can, under certain circumstances, give inaccurate estimates, e.g. if the width and height of the entry region are not sufficient to ensure that an obstacle can be passed through.